This invention relates to a machine for removing and inserting ties on a railroad track and a method for making such a machine.
In order to maintain railroad tracks in safe operating conditions, it is necessary to replace the ties periodically. The ties (made of wood, metal or concrete) underneath the rails tend to wear out after an extended period of use.
Various machines for removing and/or inserting railroad ties have been developed.
Among the prior machines for replacing ties are the machines disclosed by the following patents:
______________________________________ Patent No. Inventor Issue Date ______________________________________ 3,780,664 Holley et al. 12/25/73 4,392,433 Nyland 7/12/83 ______________________________________
The Holley et al patent shows a machine for inserting ties beneath a railroad track having a pantograph system to control the orientation of a tie clamp which is used for manipulating the tie. As common with many types of machines for removing ties, the arrangement includes rail clamps to secure the machine to the rail and a jacking system for supporting the machine on the ground while using the rail clamps to lift the rails to more easily remove or insert the tie disposed below the rail.
The Nyland patent shows a backhoe type tie remover/inserter. An articulated arm at one end of the machine is used to manipulate ties. The other end of the machine has a loader bucket as commonly used on regular backhoes. The machine has tractor wheels for running on the road and a second set of wheels for rolling along a railroad track. Vertical "outrigger" jacks may be moved horizontally and used to support the vehicle as best shown at FIG. 6. Rail clamps may be used in combination with the vertical jacks in order to raise the rail for making it easier to insert or remove a tie from a particular portion of the track.
Although the prior tie remover/inserter machines have been generally useful, they have been subject to one or more of a number of disadvantages.
Such machines have generally required a separate machine for regrading the ballast after the ties have been replaced.
A further disadvantage of many prior tie remover/inserter machines is that the machines must be specially constructed almost in their entirety. That is, some designs are ill-suited for modifying a previously existing machine such as a conventional backhoe.
A further disadvantage of some prior tie inserter/remover machines which use modified versions of conventional backhoes is that the articulated arm common to a backhoe is not well-adapted for easy manipulation of a tie. Especially where one is trying to insert or remove a tie, the tie clamp must be moved in a straight line. Using a articulated arm arrangement as in common to regular backhoes requires care in order to ensure that the rail clamp at the distal end of the articulated arm is moved in a straight line.
Although some prior tie remover/inserter machines have been vehicles which may operate on roads and on rails, it is often difficult to make such machines sufficiently narrow as to meet laws which limit the width of vehicles traveling normally on the roadways. This problem of designing the tie remover/inserter mechanism so that it does not exceed road clearance limitations may at least partly arise from the fact that prior designs generally have used a tie remover/inserter arm which is secured to a fixed pivot point the rear of the vehicle.